From: Jason Gunthorpe <jgg@ziepe.ca>
To: Mario Limonciello <superm1@kernel.org>
Cc: Mario Limonciello <mario.limonciello@amd.com>,
Alex Deucher <alexander.deucher@amd.com>,
Joerg Roedel <joro@8bytes.org>,
amd-gfx@lists.freedesktop.org,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Vasant Hegde <vasant.hegde@amd.com>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
"open list:AMD IOMMU (AMD-VI)" <iommu@lists.linux.dev>,
Jatin Kataria <jkataria@netflix.com>,
Boqun Feng <boqunf@netflix.com>,
"Derek J . Clark" <derekjohn.clark@gmail.com>
Subject: Re: [PATCH v2 1/2] iommu/amd: Add PerfOpt IOMMU performance optimization support
Date: Thu, 24 Sep 2026 21:17:18 -0300 [thread overview]
Message-ID: <20260925001718.GC163130@ziepe.ca> (raw)
In-Reply-To: <5a6ba6f3-4d8b-4d67-8e5a-ffbe22126464@kernel.org>
On Thu, Sep 24, 2026 at 07:03:56PM -0500, Mario Limonciello wrote:
>
>
> On 9/24/26 5:50 PM, Jason Gunthorpe wrote:
> > On Mon, Sep 07, 2026 at 11:12:06PM -0500, Mario Limonciello wrote:
> > > +EXPORT_SYMBOL_GPL(amd_iommu_enable_perfopt);
> >
> > Last time we hardwired the GPU and IOMMU drivers together it was a
> > huge mess to undo.
> >
> > Why does the GPU driver have to request this? Why can't the iommu
> > driver know that this is a special device that can use this magic fast
> > path and then auto set it when identity is asked for?
>
> The reason was to allow an "opt-out" path on the GPU driver.
This seems like a very poor reason for doing this given the past
negative experiances.
Jason
next prev parent reply other threads:[~2026-09-25 0:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-08 4:12 [PATCH v2 0/2] IOMMU Performance Optimization support Mario Limonciello
2026-09-08 4:12 ` [PATCH v2 1/2] iommu/amd: Add PerfOpt IOMMU performance optimization support Mario Limonciello
2026-09-24 22:50 ` Jason Gunthorpe
2026-09-25 0:03 ` Mario Limonciello
2026-09-25 0:17 ` Jason Gunthorpe [this message]
2026-09-25 0:21 ` Mario Limonciello
2026-09-25 7:20 ` Joerg Roedel
2026-09-25 12:28 ` Jason Gunthorpe
2026-09-25 13:11 ` Mario Limonciello
2026-09-25 22:39 ` Jason Gunthorpe
2026-09-26 0:33 ` Mario Limonciello
2026-09-28 12:08 ` Jason Gunthorpe
2026-09-28 15:32 ` Mario Limonciello
2026-09-28 17:11 ` Jason Gunthorpe
2026-09-28 17:15 ` Mario Limonciello
2026-09-29 2:53 ` Deucher, Alexander
2026-09-28 5:17 ` Christoph Hellwig
2026-09-25 7:30 ` Joerg Roedel
2026-09-08 4:12 ` [PATCH v2 2/2] drm/amdgpu: Enable PerfOpt IOMMU perf optimization when GPU in identity domain Mario Limonciello
2026-09-20 14:10 ` [PATCH v2 0/2] IOMMU Performance Optimization support Mario Limonciello
2026-09-20 16:27 ` Boqun Feng
2026-09-24 11:42 ` Joerg Roedel
2026-09-24 13:01 ` Deucher, Alexander
2026-09-24 13:50 ` Joerg Roedel
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